Automatic block signaling system for railroads



S. M. DAY

Jan. 18, 1938.

AUTOMATIC BLOCK SIGNALING SYSTEM FOR RAILROADS Filed Sept. 6, 1934 BY W M ATTORNEY Patented Jan. 18, 1938 AUTOMATIC BLOCK SIGNALING SYSTEM FOR RAILROADS Salisbury M. Day, Rochester, N. Y., assignor to I(general Railway Signal Company, Rochester,

Application September 6, 1934, Serial No. 742,953

Claims. (01. 246-39) .cp indication in response to the entrance of train into the adjoining track section or block, e line circuit is opened and the signal in the is held at stop, thereby affording a safety c .eck against the signal failure. r

Fig. l of the accompanying drawing illustrates cific embodiment of the invention as applied to one type of color light signal operated by alternating current over a line circuit; and Figs. 2, 2A, and 2B are explanatory diagrams illustrating the positions assumed by the contacts of such type of signal when displaying its different indications.

It is assumed that the track is divided into blocks in the usual way, each provided with one or more track circuits, each comprising a track relay TR and a track transformer TT. The circuits associated with each signal are the same; and an explanation of such circuits for the signal S will be suiiicient to make clear the nature of the invention and its application to a number of successive blocks.

The signal S is assumed to be a color light signal having a movable color screen, such as disclosed, for example, in the patent to O. S. Field,

No. 1,835,150, December 8, 1931. The movable color screen i is illustrated diagrammatically and is biased by counterweights 2 and 2A to a middle position to bring the red roundel R opposite the lamp L and lens unit, so as to display a red or stop indication, as shown in Fig. 2B. This screen I is operated by an alternating current motor device diagrammatically illustrated as comprising a rotor 3, a local winding 4, and a control winding 5. Upon energization of the control winding 5 with alternating current having one instantaneous polarity relative to the local winding 4, the color screen I is operated in one direction to provide a green or proceed indication; and when said control winding 5 is energized with the opposite polarity, a yellow or caution indication is given. When the control winding 5 is de-energized, the color screen I assumes its biased or stop position.

The control winding 5 of each signal is energized by a line circuit comprising line wires, as

n a simplified and conventional manner one spe- 6 and 1 extending to the next signal in advance in the usual way. This line circuit for signal S includes front contacts 8 of .the track relay TR at the signal Sin question, and contacts of slowrelease relays associated with the signal next in advance, and controlling the energization of this line circuit in the same Way as illustrated at sig-' nal S for controlling the energization of the line wires 6 and i by relays 9 and iii.

Each line circuit is energized by alternating 10 current from the secondary of a transformer T, havingits primary supplied with alternating current from a transmission line or other suitable source. One line wire I is connected to a midtap of the secondary of this transformer, and the 15 other line wire 6 is alternately connected to the opposite terminals of opposite polarity of this secondary by the operation of the relays 9 and H3.

Each signal S operates movable contact fingers I l and I2 attached to the counterweights 2-2a to" 20 dififerent positions to engage stationary contacts indicated by arrows, in accordance with the position of the color screen and indication displayed by the signal, in the manner disclosed in said Field patent. Figs. 2, 2A, and 2B illustrate the 5 positions of these contact members ii and i2 for the different signal indications of clear, caution,- and stop respectively; and it will be noted that these contacts control the energizing circuits of relays 9 and ill in such a way that these relays are energized if signal '8 indicates clear or cantion, and are de-energized when the signal indicates stop. The energizing circuit for relay Ii! also includes a front contact i3 of the track relay TR.

Under normal clear conditions, the track relay TB. is energized, and the contacts l'il2 of the signal S are in the position shown in Fig. 1 to energize both relays 9 and it, closing their front contacts it and E5 to connect the line wire 6 to the right-hand terminals of the secondary of the transformer T, which may be assumed to be Thus, the line circuit for the signal next in the rear is energized with a polarity which causes that signal to indicate clear. 45

When a train passes the signal S and drops the track relay 'I'R, the front contacts 8 of this relay act to de-energize the control winding 5 of this signal, and as shown also establish a shortcircuit around this winding. Assuming that the signal is in proper operating condition and indicates stop, the contacts li-i2 open the energizing circuit for relay 9 very quickly after the energizing circuit for relay in is opened at the front contact i3 of the track relay TR, so that both relays 9 and ID are deenergized and close their back contacts l4 and "5 to connect the line wire 6 to the other terminal of the secondary of the transformer T, thereby reversing the polarity of the line circuit to the signal next in the rear and causing that signal to indicate caution.

Assuming now that for some reason the signal S fails to indicate when the track relay TR drops, relay I0 is de-energized by the opening of the front contact 13 of the track relay TR, but relay 9 is maintained energized through the contacts Hl2 of the signal which is assumed to have failed. Consequently, the line circuit to the signal in the rear is held open, and that signal indicates stop. In this way, in the event of a false clear signal, advance warning is given at the signal next in the rear.

The relays 9 and ID are made slow releasing so that, when a train advances into the second block beyond the block for signal S and that signal S changes from caution to clear, a temporary opening of the contacts H and E2 of signal S in changing from the caution position shown in Fig. 2A to the clear position shown in Fig. 2 will not cause deenergization of either of relays 9 and I0 and so cause signal S to momentarily change from its clear position. The relay It has operating characteristics so that it picks up and drops substantially with the relay 9. It is important that the relay l0 should at least pick up at the same time as relay 9 when a train leaves the block for the signal S and the track relay TR picks up, otherwise there would be an out of correspondence of relays 9 and I0 and more than a harmless temporary opening of the line circuit for the signal S in the rear, which otherwise might cause that signal to give a momentary stop indication or flash of the red.

The lamp L for the signal S is preferably connected across the line wires 6 and 1 in series with a suitable resistance 20, so that this lamp is lighted only while the relays 9 and II] are in corresponding energized or de-energized positions. If the signal S should fail to indicate stop and this line circuit is deenergized as already explained, the lamp L'is extinguished, and the signal S does not display any indication. In other words, in the event of a false clear failure of the signal S, a train advancing by the signal S in the rear at stop will not receive an improper clear indication at the signal S, but rather will find a dark signal.

From the foregoing it will be apparent that the organization of devices and circuits in accordance with this invention provides for controlling three indication signals for an automatic block signaling system in a simple and eflicient manner by a polarized line circuit, and in such a way that a false clear failure of a signal is manifested by a stop indication at the signal in the rear, and the absence of any indication at the signal that has failed.

The particular structural organization illustrated and described is merely illustrative of the invention; and various adaptations and modifications may be made without departing from the invention. For example, direct current instead of alternating current may be employed for the track circuits, signals and the relays 9 and Hi.

What I claim is:-

1. In a block signaling system, signals of the movable color screen type having contacts operated by said screen in accordance with the indication displayed by the signal, a track circuit next in advance of each signal and having a track relay, a polarized line circuit associated with each signal for controlling the signal next in the rear, and means associated with each signal and at all times including and dependent upon the contacts of two slow release relays controlled by the contacts of that signal and the track relay for that signal for at all times controlling the continuity and polarity of energization of said line circuit for the signal next in the rear.

2. In a block signaling system for railroads, a signal, atrack section in advance of the signal having a track relay, contacts associated with said signal and closed only if said signal indicates clear or caution, a slow-release relay having an energizing circuit including a front contact of said track relay, another slow-release relay having an energizing circuit including said contacts of said signal, a line circuit for controlling the signal next inthe rear of said signal, and means including contacts operated by said relays for energizing said line circuit only If said relays are in corresponding energized or de-energized conditions.

3. In a signaling system of the character described, a first signal, two slow-release relays associated with said signal, a track section in ad- Vance of said signal having a track relay, one slow-release relay being de-energized only if said signal indicates stop, the other slow-release relay being de-energized when said track relay is deenergized, a polarized line circuit for controlling the signal next in the rear of said signal and causing that signal in the rear to indicate stop when said line circuit is opened, and means including contacts operated by said slow-release relays for energizing said line circuit with one polarity if both relays are energized and with the opposite polarity if both relays are de-energized, and for opening said line circuit if said relays are not in corresponding energized or de-energized conditions.

4. In a block signaling system, a color light signal having a movable color screen and a lamp, a track relay associated with a track circuit next in advance of said signal, a polarized line circuit for controlling the signal next in the rear of said signal, and means controlled by the position of the color screen and by said track relay for controlling the continuity and polarity of energization of said line circuit, said lamp for the signal being energize-d from said line circuit.

5. In a block signal system having color light signals adapted to give three distinctive indications and each having an electric lamp, a track section having a track relay next in advance of each signal, a line circuit extending from each signal to the next signal in the rear for controlling the indications of said signal in the rear, the lamp for each signal being connected across the line circuit extending to the next signal in the rear, and means associated with each signal for deenergizing the line circuit to the signal in the rear whenever the track relay associated with the first signal is de-energized and that signal fails to indicatestop.

SALISBURY M. DAY.

DISCLAIMER 2,105,905.Salisbu1'y M. Day, Rochester, N. Y. AUTOMATIC BLOCK SIGNALLING SYSTEM FOR RAILROADS. Patent dated January 18, 1938. Disclaimer filed May 18, 1940, by the assignee, General Railway Signal Company.

Hereby enters this disclaimer by disclaiming from claim 1 any system of automatic block signalling, except wherein the slow release relays act to energize the line circuit for the signal next in the rear with current of one polarity if the color screen of the signal assumes the stop position when the track relay of the track circuit next in advance is deenergized and open said line circuit when the color screen of the signal fails to assume the stop position in response to deenergization of said track relay.

[Oflicial Gazette Jane 11, 1.940.] 

